ProcDamageCreate emits a damage event - why?

Adam Jackson ajax at
Wed Mar 23 08:53:05 PDT 2011

On 3/23/11 7:24 AM, Erkki Seppala wrote:

> So what kind of guessing are we talking about here? What is the downside
> of removing this initial damage event? The downside with the current
> code is that it can lead to some excess work when no damage has
> occurred. (I wonder if the behavior can changed, though, if some
> applications already depend on it.)

I suspect that the guess, from the client's perspective, is about the 
actual window geometry at the time the damage was created.

I can easily imagine clients depending on this behaviour at this point, 
since it means you don't need to manually do a "first run" of your 
damage handler against the initial window state; you can just let your 
event loop pick it up naturally.  If you're a damage-based vnc screen 
scraper, that's a feature.

If you have an example where this does cause excess work, it'd be pretty 
easy to extend the protocol so the damage level argument includes a bit 
for (not) adding the initial clip.

- ajax

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